fakeimage | dummy image generator a la dummyimage

I have created a many to many relationship in my database.

promotions table:

I am creating my own lightbox with React and I want to set width on div with class .lightbox-active depending on image width. For now, I have set max-width: 50%; max-height: 80% for parent element and when e.g. the image is filling only 43% of parent element I want to set 43% width for a parent. Is there any way to achieve this without calculating the width in js?

I am requesting an image from cloudinary and at face value everything seems fine as I can see the image on the frontend as intended. But when looking at chrome dev tools I can see that first there was a 404 error which shows a call to the path where the image is stored but without the image name. For the second call which is successful, there is the path and the image name.

So, It appears that before the image name is not yet loaded from the state at the time the first request is made. I did try the && conditional check but that had the same result ie:

i cound't see right way how to find and modify React DOM nodes before render. For example i need to make all founded images inside component as lazy load. But the problem is that I don't know which nodes will be inserted by the user. Therefore, I need to look for them after the user places nodes in the component, by using componentWillMount or constructor i think...

Actually in jQuery, to replace real src after user insereted it in. I will do something like this: